Impact of roundoff error on the decisions of the Log Sum-Product algorithm for LDPC decoding

In this paper the impact of the roundoff error on the decisions taken by the log sum-product LDPC decoding algorithm is studied. The mechanism, by means of which roundoff alters the decisions of a finite word length implementation of the algorithm compared to the infinite precision case, is analyzed and a corresponding theoretical model is developed. Experimental results prove the validity of the proposed model.